Tension controlling means for traveling offset webs



May 19, 1931.

QMBARBER TENSION CONTROLLING MEANS FOR TRAVELING OFFSET WEBS Filed Jan. 2, 1950 INVENTOR ATTORNEYS Patented May 19, 1931 UNITED STATE HOWARD M. BARBER, OF PAWCATUCK, CONNECTICUT, ASSIGNOR TO 0. B. COTTRELL &

SONS COMPANY, OF WESTERLY, REQDEE ISLAND, A COEPORATIGN'OF DELAWARE TENSION CONTROLLING TJIEANS FOR TRAVELING- OFE'SET WEBS Application filed January 2, 1930. Serial No. 417,897.

In multicolor web perfecting presses where a traveling offset web is led around the impression cylinder of the second printing unit under the printed web, it has been difii- 5 cult to obtain clean and sharp printing.

I have discovered that if the tension on the olfset web necessary to the proper rewinding thereof be eliminated where the ofiset web is in contact with the impression cylinder of 10 the second printing unit-thus permitting the oliset and printed webs to travel together around the impression cylinder, clean and sharp printing will be obtained.

To accomplish this I provide the following means located between the second printing unit and the offset web rewinding mechamsm:

First, a guide roller for taking the ofiset web away from the impression cylinder under the same tension as the printed web; second, a compensating device for the ofiset web, and third, an ofiset web tension controlling mechanism through which the oifset web is passed and given suficient tension to produce a perfect roll in the rewinding mechanism. V

In practice, the travel of the printed web per cylinder revolution varies with the different forms used on the form cylinders thus making it next to impossible to properly proportion the guide rollers of the ofiset web tension controlling mechanism so that they will travel with the offset web under all conditions. It isto prevent this variation from disturbing the ofiset web that I interpose a compensating device between the positively driven roller for taking the offset web away from the impression cylinder and the offset web tension controlling mechanism.

A practical embodiment of my invention is represented in the accompanying drawing, in which the form and impression cylinders of the second printing unit are denoted by 1, 2, 3, 4 and 5. The traveling printed web is denoted by 6 and the traveling oii set web by 7, which offset web is shown as leading from the supply roll 8 around the impression cylinder 5 to the take-up roll 9 of the offset web rewinding mechanism. This rewinding mechanism in the present instance is shown as a compressing pair of rollers 10 and 11 driven from the gear 12 on the shaft of the impression cylinder 5through the train of gears 13, 1e, 15, 16, 17, 18, 19, 20 and21;

The ofisetjweb tension controlling mecha nism is shown herein as comprising a pluralit-y of guide rollers 22, '23, 24, around i which the offset web is passed on its way from the second printing unit to the rewinding mechanism. These guide rollers 22, 23. 24

are driven from the gear 17 through'the gears 25, 2 6, 27 at the desired speed so that the tension necessary to the correct rewindthe gears-31, 32 and 38.

The offset web compensating device is 7 shown as comprising a gravity operated take-up roller 3%, mounted in a swinging support 35 and restingupon the offset web between the guide roller 30 and the roller 22 of the oiiset web: nism. c 7

It the travel of the rollers 22, 23, 24 of the offset web tension controlling mechanismY- is slow the ofiset web s threaded with a slight slack with the compensating roller occupy- I tension controlling mechaing the position shown in long brokenlines at p a, thereby allowing the roller to maintain its pressure on the web as the slack increases. It the travel of the said rollers 22, 23, 24 of the offset web tension controlling mechanism.

is fast the offset web is threadedwith a considerable slack with the compensating roller occupying the position shown in short broken lines at 6, thereby allowing the roller to maintain its decreases.

pressure on the web as'the slack The above arrangement causes the offset and printed webs to travel together around the impression cylinder and thereby ensures clean and sharp printing on the printed web.

'It is evident that various changes maybe resorted to in the construction, form and arrangement of the several parts without departing from the spirit and scope of my invention; hence, I do not intend to be limited to the particular embodiment herein shown and described, but

\Vhat I claim is I 1. In a multicolor web perfecting printing press, a printing unit, a traveling ofiset web, an ofiset web rewinding mechanism, a web tension controlling mechanism therefor, and a web compensating device located between the printing unit and said web tension controlling mechanism.

2. In a multicolor web perfecting printing press, a printing unit, a traveling ofiset web,

an offset web rewinding mechanisnnmeans for taking the offset web away from the "printing unit under the same tenslon as the web printed thereby, an ofiset web tension oontrolllng mechanism for the rew ndmg mechanism, and a web compensating device located between the printing unit and the offset web tension controlling mechanism.

1 rollers.

3. In a multicolor web perfecting printing press, a printing unit, a travelmg ofiset web, an offset web rewindmg mechanism, web ten sion controlling rollers around which the offset web is passed on its way to the rewinding mechanism and a web compensating device comprising a take-up roller pressing against said ofiset web between the printing unit and the web tension controlling mechanism.

4. In a multicolor web perfecting printing press, a printing unit, a traveling ofiset web, an ofiset web rewinding mechanism, a roller for taking the offset web away from the printing unit under the same tension as the web printed thereby, web tension controlling rollers around which the offset web passes to the rewinding mechanism, and an ofliset web compensating roller located between said printing 'unit and said tension controlling In testimony,that I claim the foregoing as my invention, I have signed my name this 30th day ofDecember, 1929.

HOWARD M. BARBER. 

